@loopback/docs/site/apidocs/core.extensions.view.md

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---
lang: en
title: 'API docs: core.extensions.view'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/core
permalink: /doc/en/lb4/apidocs.core.extensions.view.html
---

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[Home](./index.md) &gt; [@loopback/core](./core.md) &gt; [extensions](./core.extensions.md) &gt; [view](./core.extensions.view.md)

## extensions.view() function

Inject a `ContextView` for extensions of the extension point. The view can then be listened on events such as `bind`<!-- -->, `unbind`<!-- -->, or `refresh` to react on changes of extensions.

<b>Signature:</b>

```typescript
function view(extensionPointName?: string, metadata?: InjectionMetadata): (target: Object, member: string | undefined, methodDescriptorOrParameterIndex?: number | TypedPropertyDescriptor<any> | undefined) => void;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  extensionPointName | string | Name of the extension point. If not supplied, we use the <code>name</code> tag from the extension point binding or the class name of the extension point class. If a class needs to inject extensions from multiple extension points, use different <code>extensionPointName</code> for different types of extensions. |
|  metadata | [InjectionMetadata](./context.injectionmetadata.md) | Optional injection metadata |

<b>Returns:</b>

(target: Object, member: string \| undefined, methodDescriptorOrParameterIndex?: number \| TypedPropertyDescriptor&lt;any&gt; \| undefined) =&gt; void

## Example


```ts
import {extensionPoint, extensions} from '@loopback/core';

@extensionPoint(GREETER_EXTENSION_POINT_NAME)
export class GreetingService {
 constructor(
   @extensions.view() // Inject a context view for extensions of the extension point
   private greetersView: ContextView<Greeter>,
   // ...
) {
  // ...
}
```